Ortstein and Placic Horizons - Soil Geography of the USA: A Diagnostic-Horizon Approach - page 187

Table 18.1 Statistical comparison of analytical properties of soils with 50 %

ortstein, and geographically associated Spodosols without ortstein. Data for seven soils with placic
horizons are included (Bockheim 2011 )
Property

50 % ortstein,

> <

Ortstein Some ortstein No ortstein p value Placic

Soil depth class (coded) a 3.3ab 3.8a 3.6ab 0.024 1.3

Upper boundary spodic (cm) 38a 35a 26a 0.11 30

Lower boundary spodic (cm) 95a 78ab 63b 0.001 43

Thickness spodic (cm) 57a 43ab 38b 0.001 13

Upper boundary ortstein (cm) 52a 44a na 0.35 na

Lower boundary ortstein (cm) 93a 75a na 0.283 na

Thickness ortstein (cm) or placic (mm) 41a 32a na 0.173 15

Color development equivalents 21a 19a 19a 0.407 21

Proportion of cementation (%) 70a 16b na 0 100

Degree of cementation (coded) b 3.3a 2.3b na 0 5

Fed (%) 1.0a 0.97a 1.4a 0.268 5.5

Ald (%) 0.65a 0.37a 0.69a 0.177 1.4

Alp (%) 0.43a 0.31a 0.60a 0.483 0.93

Feo (%) 0.46a 0.42a 0.74a 0.348 5.5

Alo (%) 0.69a 0.37a 0.69a 0.227 7.74

Alo-Alp (%) 0.34a 0.26a 0.35a 0.933 6.8

Fed-Feo (%) 0.58a 0.49a 0.50a 0.865 2.71

Sio (%) 0.18a 0.07a .21a 0.162 3.2

ODOE 0.41a 0.60a 0.62a 0.741 0.45

OC (%) 1.7a 1.7a 3.0a 0.108 2.98

pH 5.0a 4.9a 4.9a 0.83 4.9

Sum cations (cmolc/kg) 20a 16a 24a 0.134 45.8

Al saturation (%) 62a 61a 52a 0.394 68

Base saturation (%) 6a 9a 8a 0.461 4

Bulk density (g/cm3) 1.60a 1.55a 1.38a 0.162 1.7

Coarse fragments (% 2 mm) 7a 8a 11a 0.342 12

>

a Soil depth class: 4

¼ very deep ( 150 cm); 3 ¼ deep (150 100 cm); 2 ¼ moderately deep

>

(50-100 cm); 1 ¼ shallow ( 50 cm)

<

b Degree of cementation: 5

¼ indurated; 4 ¼ strongly cemented; 3 ¼ moderately cemented; 2 ¼

weakly cemented; 1 ¼ very weakly cemented

extremely hard dry consistence (57 %), whereas soils with 50 % ortstein and those

<

without ortstein had a consistence of slightly hard or less.
Other morphologic features of ortstein horizons include sand grains coated with
organic material in Bhm horizons of ortstein soils from FL. In 18 of the series, all of
which occur in MI, ortstein exists in columns up to 45-60 cm wide and 15-50 cm
apart. Tonguing of ortstein into underlying horizons is common in 13 of the series,
all of which occur in MI. Rinds of 5-15 mm cemented material may occur in
horizons not sufficiently cemented to be identified as ortstein. The ortstein horizon
limits but does not preclude rooting; a few fine roots were reported in ortstein
horizons of 11 pedons that were 50 % cemented.

Ortstein and placic horizons are extracted with Na pyrophosphate for Fe p
and Al p , acid NH 4 oxalate by Fe o and Al o , and Na citrate-dithionite-bicarbonate